AmericanLongRifles Forums
General discussion => Black Powder Shooting => Topic started by: Dphariss on April 18, 2009, 05:05:35 PM
-
This was originally a response to one of Daryl's posts on "No Cone" but decided it was straying from the original topic so I started a new one.
Ball fits.....
I have often wondered, as I gained in knowledge, if FFFG does not shoot better in some guns because it bumps the ball somewhat and this gives a tighter fit. This is something difficult to measure though I suppose the old oiled sawdust bullet trap might work if placed at 100 yards to let the ball slow before impact.
I know that in HEAVY bullets even FG will produce a lot of upset in the bullet. Soft bullets over 1.2 long will upset as much as .010 over the full length of the bullet.
Even a slight upset on a ball could aid the fit.
In looking at Lyman's shadow photos of RBs we see one shot with a heavy charge of powder that is flattened somewhat at the nose. I believe they state its air resistance that caused this but it is entirely possible that is was done during initial acceleration.
I also believe that heavy charges tend to seal the bore better under initial acceleration since there is powder pressed against the ball. I know that in BPCRs the lack of a over powder wad will produce very well defined powder grain impressions on the bullet base so the powder is still granulated when high pressure is put on the bullet.
There is a difference of opinion among shooters as to grain size. I see powders such as FFG, at least in the slower grinds, as too slow for the RB in most calibers. Mostly due to the balls low inertia and the fact that it does not have to forced into the rifling when it is fired. Then there is bullet fit in the cartridge case which can produce considerable initial resistance. All these thing increase load inertia and allow the powder to work more efficiently. The RB rifle has none of this. I a bore that is clean or with the fouling softened by the patch lube there is far less inertia and since the ball moves so much easier the efficiency is reduced.
I believe inertia is why larger caliber rifles get usable velocity with lower ratios of powder to ball weight as a result of this.
Now we get into fouling effecting ball movement. Shot with a lube that does not remove the fouling from the lands the increased "load inertia" of a fouled bore, the grip the fouling will produce on the ball, will cause velocity to INCREASE every shot. At least to as many as I shoot over a chronograph.
This could be why a clean bore seems to be more important at longer ranges than at close ranges since the effect of velocity variations increases with range.
Just some things to consider.
Gotta run.
Dan
-
In thinking about your post, Dan, I believe you may be on to something. The patch thread pattern is frequently found on the base of PRB and that would require a bit of "bump". Interesting to find out what others have found.
-
Dan, I don't recall the text verbiage in the Lyman Manual and am too lazy at the moment to dig it out. Air resistance cannot be the cause of flattening of the ball you reference in the photo, but obturation (bump up) certainly will occur and result in such deformation. Obturation results when pressure is applied by the charge and inertia causes resistance to acceleration of the bullet or ball. A simple comparison would be to toss a lead ball in the air and whack it with a ball bat. If you can find it after the fact it will be oblate in form. Force and inertia at work again. I don't know if there is an outer limit on how much obturation can occur...it's a computation of pressure, alloy and mass inertia. More pressure will engender more complete obturation to the point the bore dimensions allow it to occur. Dr. Mann got into this in his book and it is, as I understand it, the source of slumping in conical bullets. More lead and/or more powder equals more pressure.
The reference you give to powder grain impressions on BPCR bullets, I'm not so sure about. This may occur during the firing or loading if compression is used to seat the ball or bullet, assuming soft alloys of course. I have found this to occur with lead over smokeless too, but the observation comes from loads that are compressed.
I won't dispute your thoughts on fouling effects, making a fair bit of sense to me and all that. An increase of frictional resistance would logically increase pressure but I don't think that relates to inertia.
A fellow named Crowley discussed powder granulation and twists in a 1976 article in Muzzle Blasts. His spin was faster powder for slower twists and slower for faster etc. He was a BP bench gun builder and competitor, maybe you know of him. I don't recall he addressed the theory in his article, just referencing experience. Me, well, I cannot render valid judgment based on experience. My little picket rifle with the .38 bore and round balls shoots noticeably better with 1-1/2f Swiss than 3f Goex, which may support his idea as the rifle has a 38" twist, even if it defies conventional wisdom....or my wisdom anyway.
Dan the Other
-
Dan, I don't recall the text verbiage in the Lyman Manual and am too lazy at the moment to dig it out. Air resistance cannot be the cause of flattening of the ball you reference in the photo, but obturation (bump up) certainly will occur and result in such deformation. Obturation results when pressure is applied by the charge and inertia causes resistance to acceleration of the bullet or ball. A simple comparison would be to toss a lead ball in the air and whack it with a ball bat. If you can find it after the fact it will be oblate in form. Force and inertia at work again. I don't know if there is an outer limit on how much obturation can occur...it's a computation of pressure, alloy and mass inertia. More pressure will engender more complete obturation to the point the bore dimensions allow it to occur. Dr. Mann got into this in his book and it is, as I understand it, the source of slumping in conical bullets. More lead and/or more powder equals more pressure.
The reference you give to powder grain impressions on BPCR bullets, I'm not so sure about. This may occur during the firing or loading if compression is used to seat the ball or bullet, assuming soft alloys of course. I have found this to occur with lead over smokeless too, but the observation comes from loads that are compressed.
I won't dispute your thoughts on fouling effects, making a fair bit of sense to me and all that. An increase of frictional resistance would logically increase pressure but I don't think that relates to inertia.
A fellow named Crowley discussed powder granulation and twists in a 1976 article in Muzzle Blasts. His spin was faster powder for slower twists and slower for faster etc. He was a BP bench gun builder and competitor, maybe you know of him. I don't recall he addressed the theory in his article, just referencing experience. Me, well, I cannot render valid judgment based on experience. My little picket rifle with the .38 bore and round balls shoots noticeably better with 1-1/2f Swiss than 3f Goex, which may support his idea as the rifle has a 38" twist, even if it defies conventional wisdom....or my wisdom anyway.
Dan the Other
You miss the point, "load inertia" is different than the inertia of the bullet which is fixed by its weight. "Load inertia" is what occurs when bullet are loaded with a high bullet pull in the case, seated hard on the rifling, the powder charge is heavily compressed OR the PRB is held in place by fouling. It effectively increases the bullets inertia by making it harder to move.
Increasing the load inertia UNIFORMLY for each shot will almost always REDUCE the velocity SD.
But with the PRB it is impossible to be uniform concerning fouling in the bore. Now this can effect things in several ways. The grooves may be partly filled with fouling and this may reduce any blowby that might be occurring and increase the velocity. Of it may be the ball being jammed into fouling on the lands or a little of both.
So far as the bullet base dimples. I try to load ammo so that the bullet is just in contact with the wad or powder when seated. If the powder is to be compressed it is done in a separate operation since drop tubed powder is hard to compress very much and doing so with the bullet will tend to "swell" the nose so that bore riding noses will not chamber.
I am sure Lyman states that the air pressure or shock wave has flattened the balls nose. But the book is out of reach.
Dan
-
I can't contribute anything to the discussion, but it's something to ponder. Could the impressions in the base of the bullet, assumed to be the imprints of powder granules, actually be craters from the explosion of those granules located closest to the base? That may almost be the same thing, but seems more likely in my small mind. Either way, it's something new to me.
-
You miss the point, "load inertia" is different than the inertia of the bullet which is fixed by its weight. "Load inertia" is what occurs when bullet are loaded with a high bullet pull in the case, seated hard on the rifling, the powder charge is heavily compressed OR the PRB is held in place by fouling. It effectively increases the bullets inertia by making it harder to move.
Increasing the load inertia UNIFORMLY for each shot will almost always REDUCE the velocity SD.
But with the PRB it is impossible to be uniform concerning fouling in the bore. Now this can effect things in several ways. The grooves may be partly filled with fouling and this may reduce any blowby that might be occurring and increase the velocity. Of it may be the ball being jammed into fouling on the lands or a little of both.
So far as the bullet base dimples. I try to load ammo so that the bullet is just in contact with the wad or powder when seated. If the powder is to be compressed it is done in a separate operation since drop tubed powder is hard to compress very much and doing so with the bullet will tend to "swell" the nose so that bore riding noses will not chamber.
I am sure Lyman states that the air pressure or shock wave has flattened the balls nose. But the book is out of reach.
Dan
OK, there was a conceptual fork in the road and I took a left turn. Was looking specifically at the word "inertia" in the sense of physics, not in the sense of "effective increase" thereof. On the point of reduced velocity SD, it makes sense that it would and I think it one of reasons factories crimp their ammo. A crimp is an easier method of regulating neck tension that most any technique one might dream up. Not the best, but it provides statistical envelopes that are practical. The bullet engaged in the lands would do the same, but not to the same degree. Contrary to conventional wisdom, doing this does not raise peak pressure as much as the use of different primers in cartridge guns, and that includes jacketed bullets. In context of muzzle loaders and round balls, I think what you bring up has validity, but the variables in regulating it are vast. So we wipe....
I have a very high regard for Lyman and generally recommend their load manuals to neophytes first and foremost. That said, if they report air pressure or sonic shock waves the cause of deformation in the photo you mention, they are wrong. Now I gotta go find the danged thing and find out...... :(
-
The reference you give to powder grain impressions on BPCR bullets, I'm not so sure about. This may occur during the firing or loading if compression is used to seat the ball or bullet, assuming soft alloys of course.
I think Dphariss is on the right track with the pressure idea. I have observed those same powder granule impressions in BPC loads put together as dan describes with no seating pressure. But, the clincher for me is that I've observed those same impressions on the base of MaxiBalls loaded with only typical ram rod pressure in a .50 cal gun.
In thinking about your post, Dan, I believe you may be on to something. The patch thread pattern is frequently found on the base of PRB and that would require a bit of "bump".
I've observed that too. Here's a pic of one;
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fmikealee.home.mindspring.com%2Fimages%2FMLStuff%2Frecovered%252054ballback.JPG&hash=ae564765615e88ada45650c43eca1e4c407421ae)
But, notice that the weave is impressed around the complete base of the ball, most of which is showing since the ball was flattened on impact. So, if the pressure is applied all around the ball to impress the weave, then it would have to be applied all around the ball for the purposes of bumping the ball up. Sooo, how do we bump it up if we are squeezing it evenly from all sides toward the center of the ball?
A simple comparison would be to toss a lead ball in the air and whack it with a ball bat. If you can find it after the fact it will be oblate in form. Force and inertia at work again.
Yes, but what if we could cut a perfect half ball round depression in the bat and hit the ball with such accuracy (precision? ???) that the ball was perfectly placed in the depression when it was hit. Now what would the shape of the ball be?
When we mix comparisons of conical bullet behaviour and round ball behaviour under pressure we are comparing two entirely different things.
-
Dan,
I dug out the book, and your recollection is correct. Deformation is attributed to the shock wave.
I stand by my earlier objection to that premise.
I should have said in my last that mechanical or interference restrictions to bullet movement have influence on powder burn. Consistency in initial movement of the ball/bullet as might be plotted on the pressure curve would logically reduce SD.
Dan the Other
-
OK, there was a conceptual fork in the road and I took a left turn. Was looking specifically at the word "inertia" in the sense of physics, not in the sense of "effective increase" thereof. On the point of reduced velocity SD, it makes sense that it would and I think it one of reasons factories crimp their ammo. A crimp is an easier method of regulating neck tension that most any technique one might dream up. Not the best, but it provides statistical envelopes that are practical. The bullet engaged in the lands would do the same, but not to the same degree. Contrary to conventional wisdom, doing this does not raise peak pressure as much as the use of different primers in cartridge guns, and that includes jacketed bullets. In context of muzzle loaders and round balls, I think what you bring up has validity, but the variables in regulating it are vast. So we wipe....
I have a very high regard for Lyman and generally recommend their load manuals to neophytes first and foremost. That said, if they report air pressure or sonic shock waves the cause of deformation in the photo you mention, they are wrong. Now I gotta go find the danged thing and find out...... :(
Note this was written while you were posting your finding of the photo.
But will post anyway.
A friend of mine laid "load inertia" on me sometime back but its a perfect description so I use it too. Saves a lot of words.
Pg 167 of the 1975 copyright edition of their "Blackpowder Handbook"
.
"Fig. 9 Shadowgraph of a .445 RB at 2220 fps Velocity. Note the flattening of the ball by the pressure behind the shockwave."
Looking at it I think its distortion of the shadowgraph by the shockwave or ?. I have not looked at this photo in years and took it at face value years ago.
The problem with crimp is that it more often than not hurts accuracy. Lead bullets especially soft ones don't like being pushed though a crimp. But sometimes it helps. BPCRs can be horribly individualistic especially when different reamers are used even for the same cartridge.
BP is far different that smokeless in cartridges. A gap much larger than .010 between case length and chamber length will often result in lead or paper rings at the case mouth as the powder bumps the bullet before it starts to move.
The BPCR shooters work load inertia in various ways, some use no neck tension at all and generally use some bandaid approach like very heavy compression but its not a good answer IMO.
Little of this is applicable to MLs. But ML arms do benefit from drop tubes but they are only practical as range accessories at matches.
Some shooters report heavy compression in MLs helping with accuracy but there is no way to get much compression on powder by hand, some mechanical advantage is needed to produce more than 1/8" of compression on drop tubed powder charges. Yes, I have actually tested this with a arbor press with a scale to measure handle pressure and a cartridge case with a false bottom in a chambered chunk of barrel. Crude perhaps its still informative.
While most ML charges are not properly drop tubed, the powder is generally poured too fast and the inside of the barrel is not smooth which could also effect compaction as well. Properly drop tubed powder, especially Swiss is pretty hard to compress. The PSI at the punch face gets pretty high once past about 5/16-3/8". Compression is WAY past "pushing on a rod" pressure at about 1/8 to 3/16. So I do not consider compressing the powder practical in a ML.
Properly drop tubed (cartridge loading) is poured at a consistent rate for each cartridge taking perhaps 5 seconds for the typical charge of powder. Pouring too fast greatly reduces compaction. Some shooters vibrate the cases.
Uniform compaction via drop tube or vibration, allows a uniform compression of the charge for a uniform seating depth. It also produces more uniform ballistics, so uniform that the SD gets down to the accuracy error of chronographs. It also greatly reduced fouling in the bore.
Why? *Probably* due to the way the flame propagates in the charge.
So careful drop tubing is surely a good idea in MLs and this is confirmed by its use by ML slug gun and picket rifle shooters.
It really helps (from reliable "rifle cranks") though I have not tried it personally. The tube must end about 1/2" above the highest level of the powder in the bore to be effective.
Note than many straight case BPCR shoot best with NO compression at all. But without compression transporting the ammo will cause vertical dispersion problems so about 1/16" or a little less is recommended. I used to use 1/8 for BN cases with GOEX.
In some testing, limited, I found the lubing the bore after cleaning seems to help my experimental picket rifle's accuracy. But this is not set in stone.
I suspect it will shoot as well or better with 1.5 Swiss as FFG. So far best groups have been 80 grs of FFG Swiss in a 40 with a 132-135 grain swaged FP, FB picket. But its still nothing to right home about, probably 2-3" at 100. 70 grain group is much bigger.
Why the picket takes so much powder I have no idea but it seems to be fairly typical.
This is a 48" twist and perhaps the twist needs more powder.
But then Chapman tells of using 2" of powder in the bore for a 38 picket rifle with a gain twist and if IIRC it ends in the 30s twist range. Would have to re-read to be sure.
He indicates that hot powders do not work as well with the picket.
Sorry about all the BRCR content but there has been a lot more serious shooting done with BPCRs over the past 20 years than with PRBs. Lots of shooters shoot a LOT with sophisticated sights at ranges to 1000 yards and even beyond. There is a measured mile match in Northern Wyoming and some people are VERY serious about this. Then we have the Schuetzen shooters who try to shoot 250s at 200 yards and the 25 ring is not all that big.... The level of development is pretty darned impressive. But they are still having problems beating some of the old records.
We have people doing a lot of very good work with MLs to but the numbers are not as high. Few ML shooters chrono all their target work as well as shooting for group. It is amazing what can be learned with one of these speed meters. Some pretty heavy BPCR shooters are buying ML picket and slug guns and shooting these as well. Some of these were ML shooters who, like me, drifted to BPCRs. It was a living and shooting 200-1000 yards is a lot of fun. But BPCR is also a lot of work and I shudder at detailed load development these days. To much stress ::)
Hope this makes sense.
Dan
-
Dphariss--- I cannot speak from a lot of experience in the realm of conical bullet ballistics. However in the realm of PRB ballistics it is another matter. I do not have a chronograph but I have and use a so called "proofing bench" for testing the integral accuracy of muzzle loading gun barrels. So I think you are on to something here! It has been a longtime belief of mine that soft round lead balls do indeed obdurate when subjected to the blast of exploding black powder that is placed behind them. Perhaps not with the same amount lateral tension as a conical but never the less they will have the same tendency to upset. I also believe that if given a place expand laterally they will. Since a patched round ball is being loaded from the muzzle ,the patch and ball are squeezed to the specific dia. of the bore being loaded and the rifling is then "engraved" onto the soft lead ball through the patch. As the load is forced down to the breech the projectile stays the same dia. as when it was first loaded in the muzzle. Now if that soft lead ball had a slightly larger surrounding at the breech than the muzzle, when it "bumps up" it will, in effect, be re engraved as it travels towards the muzzle. Thus providing a tighter grip on the PRB by the lands all the way to the muzzle. What I am talking about here is a tapered bore. My tests on the proofing bench showed that a tapered bore produced better groups than a parallel bore. Of course that is why I taper my bores before I rifle them--.004-.006" larger at the breech than the muzzle. This concept is not a new one it was under stood and practised many decades before I started rifling barrels--- Bill Large for one, and I believe that the Hawken boys did similar things to their bores on the famous "Hawken" rifles. Just something more to ponder. :-\ Hugh Toenjes
-
Interesting...Point and question,
With consistent pouring of powder at the muzzle, doesn't the rifle barrel act as a drop tube? Perhaps a little more consistent with a smoothbore due to fact of being that,smooth bored as opposed to rifles.
-
Dan,
I am in agreement with your analysis of BPCR and lack of detailed analysis in the PRB reference internal ballistics. It has the appearance of something Mr. Pletcher might shed some light on, no? (I love to volunteer other people ;D)
Having spent some time in study on the matter of exterior ballistics and Florida Statute, I am stricken by the propensity to divide these things into narrow focus elements for analysis. I think it would work in this case if one if judicious. To that end, we are in agreement that PRB and BPCR have little in common other than lead and powder. I would argue that there is little in common between PRB rifles and slug guns, or picket rifles as well. Ergo, time is best spent with sole attention to the issue at hand.
Given:
1) One cannot compress BP in meaningful amounts with a ram rod.
2) Consistent compacting of BP contributes to reduction of velocity variations. I differentiate "compression" from "compacting" in that one requires mechanical advantage while the other relies on minimizing airspace in the charge (drop tube).
3) There is advantage to be found in regulating the point in the pressure curve wherein the PRB begins to move.
a. The factors that influence which are within our direct control are, with all else equal, ball diameter, patch material and thickness, alloy, charge quality and quantity, lube efficiency and bore condition. (I likely left something out here, but it's a start.)
b. A factor that has influence but is difficult to regulate to advantage is fouling. Fully cleaning the bore between shots is problematic and obviates perceived advantage to regulating load inertia.
c. For purposes of this discussion, "load inertia" is defined as those aspects of the charge (patch, powder and ball) which contribute to consistency and reduction of velocity variations. They are mechanical in nature. EX: interference fit between bore and charge. See paragraph 3a.
Find:
Identify actions or aspects of this process which will contribute to ballistic consistency and may be intentionally manipulated by the shooter with the single objective of increasing accuracy in PRB rifles.
Before we go further in this discussion, I would like review of the above in order to provide focus on the discussion. There is no pride in the preceding text and it may be modified or beat to death at will, by one and all. My desire is to pursue the investigation logically and perhaps answer a few questions along the way, or provide catalyst to analysis to specific elements which may not have been thoroughly addressed in years past...our past. There are interesting points on the table... What say ye?
-
Most Interesting, and good thread, DanPhar - for those inclined toward the technical aspects of shooting. I've got to pick Carol up for the Sunday shoot soon and will comment later when I've had some time to think about all the great posts so far. Thanks for the headaches to develop as I do this, guys. Good stuff.
Hugh - no chronograph?- in this day and age - interesting. Gads, :o I thought everyone had a at least one chronograph. ;D just fooling with you - :-*
-
I question the comment on the lack of work done on getting accurate loads in ML's and patched round balls as much as the fact that it has been done but due to the lack of variables has not been pursued as in elongated bullet work. Part of the issue is in the nature of a round ball, where to get more weight you have to get a larger ball and the other part is the nature of the patch, ball combination for reloading. At the ranges round ball loads are shot, chronographs do not mean much. Accurate loads in a patched round ball are achieved by the use of a very tight (as in sometimes seated with a mallet) loads. Some use ball diameters that are larger than the land to land diameter of the bore. Also the larger bores at 50 and above seem to be the rule as they are the most accurate at longer ranges. When I chronographed a few loads a while back I found that 2f gave considerably less shot to shot deviation than 3f in my 54. This is generally accepted for larger bores. Daryl has mentioned the use of 2f even in a 40 as being more consistant. Another thing is that if one uses one half weight powder to ball weight as in 110 grains in a 54 to its 220 grain ball weight one sees a higher velocity with the smaller bores. This is due simply to the scaler effect of spheres, where the surface area increases by the radius squared while the volume increases by the radius cubed. There is less available surface area for the gases to push against per grain weight of the ball as the diameter increases. A mention was once made that small bores also seem to lose effenciency, which may be explained by the fact that the surface areas is appreciably larger and the ball is accelerated easier permitting less pressure buildup. Also powder granulation seems to be related to bore size in that 3f in a 32 may be roughly like 2f in a 50. This "inertia" you are considering is the scaler effect.
DP
-
Northmn, I'm thinking its a relative comparison. Cartridge guns are much more tractable in analysis than muzzle loaders so far as internal ballistics factors. On another angle, PRB shooters are likely more prone to pragmatic lateral problem solving. By that I mean they are looking for "good enough" and will change dimensions or components until it is good enough rather than the best. Determing what is "best" may be difficult with a flint lock in its own right. Doesn't describe all folks I know, but there are a great many variables in the process and by nature of the arms it is difficult to state definitively what results in what inside the bowels of a PRB gun.
An example of one variable is that of a tapered bore, as indicated by Blacksmoke. With a chamber area of the barrel .004-.006" over muzzle diameter it is reasonable to conclude there is less consistent resistance to initial ball movement before the onset of obturation. BP seems to generate greater velocity variation under such circumstances and in context of the discussion less load inertia. I've found good accuracy with tapered bores in other arms, but see no basis to conclude one way or another that it is beneficial for PBR rifles. Such might be resolved by analytical testing.
-
Those that shoot the "rest" type matches such as X sticks, bench or even chunk, continue to experiment beyond good enough. Here they use false muzzles and other loading aids. Consider that a 45 BPC can use bullets ranging from 300 grains to 550 and you see a considerable range of variables in that alone. Generally the long range BPC use a 1-18 twist and a heavy 500 grain + bullet. A PRB ML has ball diameter as a variable, but that is reasonably limited. We have discussed ad nausium, twist rate for a ML and one would find that that will vary on a firing range, but many bench rest like a slower twist as they may use heavier charges to get the velocities up. Patches vary from Teflon coated to regular patches. Lubes are tried. Basically I think you are selling the round ball shooters short by saying they do not test loads and experiment, its just that the game is a little different. A flintlock by nature is going to give a more erratic ignition than a cap lock, and a cap lock a more erratic ignition than an enclosed catridge. Consider that some have used enclosed nipples taking centerfire primers for ML competition. Also inlines existed on the target ranges long before Knight came out with his contraptions, we called them zip guns. People that compete at these levels are very analytical, but as in BPC, you will see different theories and those different theories win often enough so that conclusions may be difficult. To see if Blacksmokes ideas will win, that type of barrel needs to be used in an appropriate configuration in these matches. The precision of a hand lapped match barrel whether choked, tapered or straight is such that it takes a scope to test any differences and they will be very small as in fractions of an inch.
DP
-
Not selling anyone short, just looking at the vast amount of research on this subject... ::)
And I don't find the ancillary illustrations pertinent.
-
I got in on this topic in pieces because of lack of time the past two days. I just reread the topic and find it fasinating. I'm not sure where this is headed but will follow it with great interest. Has anyone played with a capture system- oil-soaked -sawdust for instance?
Steve Chapman and I have experimented with load compression and accuracy with RB but want to repeat the trials with another gun. We began to see trends but were't satisfied with our control of variables. What we did may not be relevant to the topic anyway.
Regards,
Pletch
-
The problem with trying to use fouling to create load inertia is that its not consistent.
The constant increase in fouling causes an increase in velocity, at least in some cases.
I do not consider it as a way to gain so far as uniform ballistics.
Northmn:
"Another thing is that if one uses one half weight powder to ball weight as in 110 grains in a 54 to its 220 grain ball weight one sees a higher velocity with the smaller bores. This is due simply to the scaler effect of spheres, where the surface area increases by the radius squared while the volume increases by the radius cubed. There is less available surface area for the gases to push against per grain weight of the ball as the diameter increases."
If you check Lymans BP handbook you will find that 1/2 ball weight of FFFG powder in a .36 with a 32" barrel produces 1579 fps
A 32" barreled 50 with 90 grains FFFG makes 1891fps
My 16 bore rifle with a 30" Nock breech barrel makes 1600 with a 140 gr Swiss FFG and 1650 with 150 gr. With this ball weight (437) 150 is just over 1/3 ball weight.
A 50 will produce similar velocities with the same ratio of FFFG powder. According to Lyman.
The 36 makes 1335 with a similar ratio of FFFG.
If we change the 36 and 50 loads to FFG the velocity will fall off significantly.
Is this due to inertia of the larger ball or to the bore size allowing more of the charge to light faster I cannot say. But remember the more you restrain BP the more efficient it becomes. Be it in firearms or blasting rock.
So far as the BPCR experimentation. I did not intend to short change the RB shooters in the comments on the amount of experimentation being done.
But then one must remember that to really wring out a BPCR you, in theory at least, need to try at least 20 different primers alone. For example LR, LP, LRM, LPM and then the match primers and then the other brands. 10-15 rounds with each possible primer is going to be 200-300 rounds easily.
Then there are several brands of powder in various granulations, then bullet lubes, alloys, bullet designs, over powder wads.
Now with experience and the help of friends you might narrow the primers to 4 or 6 (maybe only 40-100 rounds testing primers) and not test the rest. We know that there are basically 3 lead alloys to try 1:20, 1:30, 1:40. But I once had a bullet that would not shoot soft and needed #2 alloy (hard) alloy.
The RB rifle is not this complex. Maybe 4 different powders, 2-3 different ball sizes, then play with patches and lubes.
Then add in that every new lot of primers is another variable. Shooters would find a "good" lot primers or of Goex and buy all they could because the next lot required them to start over with the primers, compression etc since it was different and groups went south with the new powder loaded like the old powder.
I started this thread to provoke thought and see what other experiences there were. Through this more experimentation is done, more people relate experiences and we ALL learn.
Does EVERYONES rifle gain in velocity as it fouls??
Another thing about drop tubes. Some shooters did not want the bullet/ball running into powder grains adhering to the barrel as it was pushed down. They thought it would hurt accuracy.
The picket bullet is not a patched RB. But it uses the same patches and lubes and like the Kentucky rifle its an American original, or so I read. Its is also a HC projectile from 1830 onward that saw wide spread use. Look at the Gumph marked bullet mould in Whiskers "Gunsmiths of Lancaster County" three different bullet shapes. The heavy slug gun is also an American inventions so far as I know and predates the American Civil War.
I further submit that thinking that the round ball shooter can gain nothing from the experiences of picket and slug shooters is just silly. Especially if you have percussion rifles.
Dan
-
I thought the above post was sent this AM and got back to the computer and its still setting there.
So its a few hours late ???
Dan
-
Northmn, I'm thinking its a relative comparison. Cartridge guns are much more tractable in analysis than muzzle loaders so far as internal ballistics factors. On another angle, PRB shooters are likely more prone to pragmatic lateral problem solving. By that I mean they are looking for "good enough" and will change dimensions or components until it is good enough rather than the best. Determing what is "best" may be difficult with a flint lock in its own right. Doesn't describe all folks I know, but there are a great many variables in the process and by nature of the arms it is difficult to state definitively what results in what inside the bowels of a PRB gun.
An example of one variable is that of a tapered bore, as indicated by Blacksmoke. With a chamber area of the barrel .004-.006" over muzzle diameter it is reasonable to conclude there is less consistent resistance to initial ball movement before the onset of obturation. BP seems to generate greater velocity variation under such circumstances and in context of the discussion less load inertia. I've found good accuracy with tapered bores in other arms, but see no basis to conclude one way or another that it is beneficial for PBR rifles. Such might be resolved by analytical testing.
Choking a PRB barrel will often help the accuracy. it also helps ease the loading.
Dan
-
Well, I'm thinking.... ;D
In consideration of tapered bores, yes there are parallels between PBR rifles and the others but the variables cloud the analytical processes. As an example, the physical dynamics are different between conicals and round balls due to inertia (the physics definition). Conical bullets are likely more affected by obturation and that point is subject to variables based on charge weight and alloy. They use no patch, or in some cases, a thin paper patch and the differences in gas seal between conicals and PRBs is not clear to me. How different patch material (paper/cloth) affect obturation is not clear to me. The higher sectional density of conicals would also contribute to greatly to the concept of load inertia and comparatively would moderate the effects of loose fit of the bullet in the early phase of the firing sequence. I would opine that tapered bores would stand against the load inertia concept, even if they shoot well. Therein is found a conundrum.
The matter of using fouling to regulate load inertia was at first....messy on a conceptual basis, at least to my fuzzy brain. After some thought I don't know that it is. The objective is consistency first and foremost and secondarily perhaps to assist in containing the charge during ignition. There is a parallel with the BP bench guns here, but I've seen no thorough analytical research on the point. The slug gunners and BPCR shooters of today seem to have various pet methods which include blow tubes, a certain number of wipes with this and wipes with that, and of course humidity plays as does the type of lube. One variable after another, and on top of that one of our current shooters with champion pedigree has stated that he doesn't give the process all the same energy and detail that he once did. I fall back to my earlier statement of "good enough". It is not necessary to clean the bore between shots, only to do so consistently and in incremental stages to examine this issue. A chronograph will give the truth to the issue.
If the goal is to segregate those things which contribute to reduced standard deviations in PRB rifles it will be necessary to to test each individual component in depth with that specific variable.
What I think could come out of this is a collaboration amongst forum members to look into this. I do think the "all else being equal" clause can be used appropriately and with exception of the tapered bore/straight bore analysis, each element can and should be done by one person and one gun, analyzing component variables such as primer caps, lube, etc etc.
I have at present, a flint lock of .45 caliber, and a .38 bore picket cap lock, both of which do well with round balls. The picket has a choked muzzle, the flinter is straight of bore. Two brands and two granulations of powder and 4 varieties of caps rest in waiting. I can retrieve my Chrony quickly enough and am willing to explore this in concert with others here on the forum but do not have the time to do the whole banana. If we want to pursue this, let the consensus develope as to who does what and what the issues are to be examined...then I will pitch in. I think it would be an interesting collaboration for Muzzle Blasts.
-
I got in on this topic in pieces because of lack of time the past two days. I just reread the topic and find it fasinating. I'm not sure where this is headed but will follow it with great interest. Has anyone played with a capture system- oil-soaked -sawdust for instance?
Steve Chapman and I have experimented with load compression and accuracy with RB but want to repeat the trials with another gun. We began to see trends but were't satisfied with our control of variables. What we did may not be relevant to the topic anyway.
Regards,
Pletch
Larry,
I've been pondering the compression issue and while in agreement with Dan that PRB ML compression is problematic, it occurs that it might be possible to affect such with various contrivances such as a cam or lever assembly which clamps on the muzzle, and a steel rod. Not practical for field work, but might get the job done for purposes of this inquiry. Can you describe how you approached the problem? I think it would be meaningful to pursue this but am uncertain of the application of findings after the fact.
Dan the Other
-
Snipped . . . . Can you describe how you approached the problem? I think it would be meaningful to pursue this but am uncertain of the application of findings after the fact.
Dan the Other
Dan,
Steve and I used a collar on a steel bench rod to control compression. We moved the collar in 1/16" increments and measured compression in inches as the BPCR shooters do.
We hurried the project along and now wished we would have changed a few things. I wrote this up on a web page and our proceedures and changes for future testing are located there:
http://www.blackpowdermag.com/featured-articles/load-compression-and-accuracy.php (http://www.blackpowdermag.com/featured-articles/load-compression-and-accuracy.php)
Our conclusion was that compression helped both flint and percussion rifles, but we want to redo the test with the changes noted.
Regards,
Pletch
-
Larry, thanks for that. Noticed a chronograph in one of the pictures, do you still have the velocity information?
-
The problem with trying to use fouling to create load inertia is that its not consistent.
The constant increase in fouling causes an increase in velocity, at least in some cases.
I do not consider it as a way to gain so far as uniform ballistics.
Northmn:
If you check Lymans BP handbook you will find that 1/2 ball weight of FFFG powder in a .36 with a 32" barrel produces 1579 fps
A 32" barreled 50 with 90 grains FFFG makes 1891fps
My 16 bore rifle with a 30" Nock breech barrel makes 1600 with a 140 gr Swiss FFG and 1650 with 150 gr. With this ball weight (437) 150 is just over 1/3 ball weight.
A 50 will produce similar velocities with the same ratio of FFFG powder. According to Lyman.
The 36 makes 1335 with a similar ratio of FFFG.
If we change the 36 and 50 loads to FFG the velocity will fall off significantly.
Is this due to inertia of the larger ball or to the bore size allowing more of the charge to light faster I cannot say. But remember the more you restrain BP the more efficient it becomes. Be it in firearms or blasting rock.
So far as the BPCR experimentation. I did not intend to short change the RB shooters in the comments on the amount of experimentation being done.
But then one must remember that to really wring out a BPCR you, in theory at least, need to try at least 20 different primers alone. For example LR, LP, LRM, LPM and then the match primers and then the other brands. 10-15 rounds with each possible primer is going to be 200-300 rounds easily.
Then there are several brands of powder in various granulations, then bullet lubes, alloys, bullet designs, over powder wads.
Now with experience and the help of friends you might narrow the primers to 4 or 6 (maybe only 40-100 rounds testing primers) and not test the rest. We know that there are basically 3 lead alloys to try 1:20, 1:30, 1:40. But I once had a bullet that would not shoot soft and needed #2 alloy (hard) alloy.
The RB rifle is not this complex. Maybe 4 different powders, 2-3 different ball sizes, then play with patches and lubes.
I started this thread to provoke thought and see what other experiences there were. Through this more experimentation is done, more people relate experiences and we ALL learn.
Does EVERYONES rifle gain in velocity as it fouls??
Another thing about drop tubes. Some shooters did not want the bullet/ball running into powder grains adhering to the barrel as it was pushed down. They thought it would hurt accuracy.
I further submit that thinking that the round ball shooter can gain nothing from the experiences of picket and slug shooters is just silly. Especially if you have percussion rifles.
Dan
I thought I mentioned that the smaller bores also do not gain at the same rate because they have a higher surface area to mass ratio than a mid size bore and may start too easily.
My point was also that round ball shooters do not have all the variables that a BPC has.
I just dug out my copy of "Muzzle Loading Shooting and Winning with the Champions" Copyright 1973. BPC is a relative newcomer in popularity to the BP sports as far as press coverage anyway. The big matches did not exist in 1973, and yet a great deal of research had already been done on PRB accuracy by that time. Some common comments in the book were that for match shooting one needs to use a ladle for casting more consistant round balls. Weigh the ball within .3 of one grain, Patch thickness and ball fit are critical to accuracy. One used a mallet to seat his ball. Keep a note book for what works and what works on some days as in temp. FIRE A FOULING SHOT. Do not load so tight you deform the ball too much, use false muzzles and lapped barrels. A comment was made about barrel types, including choked ones and the fact that with proper load development they all work. Another about working out so you can lift bench rifles to the bench.
My point is that a lot of work has already been done over a generation ago. Many of the "new" ideas have been tried, and wheel reinvented. Can the picket bullet experimentation help PRB shooting. It may. There have been a few technological developments since then such as teflon coated patches. But a lot of what we take for granted has been used and proven on the range.
As to foulings effect on velocity. When I chronographed several different loads a while back and posted them, I found that without exception, the first shots were lower velocity than the succeeding shots, even when wiping between shots. The most consistant velocities in my 3 rifles tried came after one or two shots and no wiping. Daryl has also mentioned that he has noticed this. Note the use of a fouling shot in my previous comments from bench/buffalo shooters.
Another point is that to really ring out the patched round ball in percussion, one has to start with a rifle built around a 1 1/8 inch barrel in 50 or 54. These were the most popular rifles back then and I am willing to bet still are. Most of out "rules of thumb" revolve around a group of calibers in the 40-54 class. Larger bores and smaller bores start to follow different rules due to dimensional shifts such as the scaler effect.
DP
-
I guess to clarify, the PRB shooting sports have been established for some time with considerable research already in place. Blacksmoke makes good barrels judging by his pictures of groups. They will not shave off an inch from other barrels because there is no longer an inch to shave off. Any developments will be small refinements of what is already in place. While it is true that it is ridiculous to think that experiments with picket bullets or whatever may not be able to add anything, it is also arrogance to assume that anything earthshaking can be added to a refined and established sport. If PRB shooting has any limitations it is in the fact that the events are commonly held at 50 and 100 yards. It is possible that stretching the ranges, say 200, like suggested, would be more likely to wring out their capabilities. 50 yards is a pistol range.
DP
-
Any developments will be small refinements of what is already in place. While it is true that it is ridiculous to think that experiments with picket bullets or whatever may not be able to add anything, it is also arrogance to assume that anything earthshaking can be added to a refined and established sport.
DP
I don't recall anyone implying that earthshaking things would come from this and do not see anything wrong with small refinements. Your thoughts seem broad ranging on the subject. If you have knowledge of specific research on this topic I would welcome direction. I am admittedly less well versed on the subject of PRB rifles than a great many folks that post here, but on the matter of ballistics I am reasonably educated. Dphariss has raised a question pertaining to internal ballistics that appears worthy of examination and it deals with a very specific aspect of load management with muzzle loaders using PRBs.
While it is true that it is ridiculous to think that experiments with picket bullets or whatever may not be able to add anything
In context of the discussion, would you be so kind as to describe what congruent elements might be found in picket bullets and PRBs. Honest question....standing by here.
Dan the Other
-
Sounds like a lot of neat scientific stuff, but personaly I just pour in the powder drop in some hornets nest or a wad, then a ball then another wad or more nest. I haven't a clue where the inertia goes or if I ever had any...
I never saw any on any of the deer , squirrels or other game I shot so maybe I didn't have any, but things worked out ok anyway.so I must not have needed any.
-
I made reference to a book over 30 years old that pointed out the fact that the subject has been "researched" by serious competitors. Dpharsis could very easily with his knowledge construct and know how to build a PRB rifle that could shoot X-rings. That type of shooting is not popular on this web site as most have TG's attitude. I do not think I have seen anyone, since I have viewed the website, build or showoff, a halfstock rifle with a match grade barrel at 1 1/8 inches, 50-54 caliber, 35 inches long, with a top grade percusiion lock and triggers. If you really want to get into it you build it around an inline or underhammer action to put more weight in the barrel. That is the specs for light bench or an X sticks guns weighing under 14 pounds. Add a false muzzle. The loads are ball diameters at bore diameter or even slightly over (for heavy powder charges) and a heavy patch. Mallet loaded. Personally, while I have thought about building one, I would not have much use for it, because like TG, I just want to enjoy my shooting at a much less restrictive level. The biggest restriction on PRB is the ball itself as the wind plays hob with it and it does not retain velocity well. Picket bullets and other bullets replaced the round ball because they are quite simply, more efficient ballistically. The developments in BPC have been toward using a very heavy pointed bullet.
DP
-
OK, thinking here I'm seeing a difference in perspective on what this is about. As I understand the topic, there is a question about load/charge variables specific to velocity extreme spreads and standard deviation. Furthermore, the question goes directly to those aspects defined as load inertia. These things are related to accuracy for sure, but review of targets, regardless of range will shed little light on what's going on in the south end of the barrel. By the time a bullet or ball exits the muzzle differences in internal dynamics will promote variations in barrel harmonics and increase dispersion. One may infer consistency based on target analysis but there is no way to weight the random influence of wind or projectile variations...or gnats. Therefore, the conclusions reached by target analysis may or may not be valid.
There is a method of load development often used for white powder shooters called the Ladder Method, that being wholly focused on barrel harmonics and the identification of vibration nodes in the barrel. I would suspect that long barreled muzzle loaders are very much affected by this issue. I would also point out that minimum SD is not a guarantee of small dispersion. My point goes back to something stated in one of my earlier posts on this topic; that it is necessary to segregate the variables to properly analyze them in a statistical sense. What comes out of it may well be a grab bag of information of small value, but one never knows until they explore.
Barring published reference on the specific point raised in this thread, I would necessarily conclude it does not exist. I've read more than a few books on the subject of black powder guns and seen no direct reference to the subject. I have seen a lot of commentary that dances around the subject, but nothing to indicate specific focus. Most discussion that comes close relates to conical bullets. I certainly understand the reasons behind picket and conical bullet development, but for every possible basis of internal ballistic comparison to PRBs, I see fundamental ballistic science basis to object to the comparison. My imagination is somewhat limited though...
Admittedly, I have not made it all the way through the Warner-Lowe letters, but I'm working on it.
Dan the Semi-Ignorant
-
Yes it does make sense. Colt tapered the bore on their exquisite Python revolver and probably others as well. No one ever accused the Python of being inaccurate. ;D
-
I made reference to a book over 30 years old that pointed out the fact that the subject has been "researched" by serious competitors. Dpharsis could very easily with his knowledge construct and know how to build a PRB rifle that could shoot X-rings. That type of shooting is not popular on this web site as most have TG's attitude. I do not think I have seen anyone, since I have viewed the website, build or showoff, a halfstock rifle with a match grade barrel at 1 1/8 inches, 50-54 caliber, 35 inches long, with a top grade percusiion lock and triggers. If you really want to get into it you build it around an inline or underhammer action to put more weight in the barrel. That is the specs for light bench or an X sticks guns weighing under 14 pounds. Add a false muzzle. The loads are ball diameters at bore diameter or even slightly over (for heavy powder charges) and a heavy patch. Mallet loaded. Personally, while I have thought about building one, I would not have much use for it, because like TG, I just want to enjoy my shooting at a much less restrictive level. The biggest restriction on PRB is the ball itself as the wind plays hob with it and it does not retain velocity well. Picket bullets and other bullets replaced the round ball because they are quite simply, more efficient ballistically. The developments in BPC have been toward using a very heavy pointed bullet.
DP
The BPCR "technology" was basically lost when Dupont destroyed the powder industry in the US circa 1900 and blackpowder primers disappeared about WW-I when the makers essentially doubled the amount of compound in all the primers. This last REALLY hurt.
The primer change alone destroyed accuracy for shooters like Harry Pope and they only go it back by using smokeless in some manner. So BP disappeared in the cartridge world for any serious shooting. We lost the "link" to the old target shooters and much of what was available was for schuetzen shooting and no longer worked without using smokeless.
It was so bad that at least one pretty big name in shooting stated that accuracy with BP loaded cartridges was impossible. Not only did we not know how, one key component, a "soft" primer, had not even been made for about 60-70 years.
We had a few books and such and more have since come to light. But one of the "light bulb" moments for me was reading Rywells book with the Sharps catalog reprints. An old catalog reprint told how to load shells and it WORKED.
Eventually I was telling people that they needed to forget 75%, or more, or what they "knew" about smokeless reloading to load for BPCR. Some "laws" for successful smokeless reloading often do not apply and are sometimes 180 degrees out.
MLs on the other hand never completely died. The loss of powder makers did not effect them as much, the "primers" did not change. People were still shooting MLs the old way. What a 1980s a new to ML shooter could draw on NMLRA matches/experience that had been running for decades. When I started in the mid 1960s I could learn the basics, good info, by reading Muzzle Blasts. A greenhorn could load a rifle with about 1/2 ball weight of powder +-, a .005-.010"under ball, a heavy patch with almost any lube and it will shoot pretty well if the barrel is OK.
When serious BPCR competition came into being we had a lot of competitors, good shots with decent rifles, who were loading ammo that would not hit the backstop every shot at 300 yards, the easy target in silhouette.
Other things.
The conical, the Minie and picket bullet certainly did not universally replace the RB in hunting rifles. The picket especially took over for long range and a lot of target work in the 1830s-40s. But the extra powder and lead needed, the exacting process and the tools generally needed made them a little too complex for the average squirrel hunter. The Minie was easy to load but was prone to sliding off the powder and was very limited as to its velocity due to its large hollow base, it was unsuitable for subsistence hunting. The slug gun evolved but was more impractical for general use than the picket.
Elongated projectiles do upset and fill the bore as Mann wrote in "The Bullets Flight". In fact Mann believed the lead bullet was to easy to deform at higher pressures. The PP bullets used in slug guns and BPCRs *must* do so failure to upset will blow the patch. I have shot cylindrical PP/GG bullets that were near or under *bore* diameter for their full length in both ML and BPCR and they work fine and do not gas cut. This is how the various "naked" modern ML bullets work.
"Reinventing the wheel". A lot of this has gone on since, in some cases, the "wheel" had been lost. Yes some have even rewritten history to sell products or for other reasons and not just concerning projectiles.
Yes, this may be "too scientific". But suspect that everyone here is using their rifle/gun in a manner that was figured out by someone who was "too scientific". Some "rifle crank" will post something here and it goes into everyone's "data" base when they read it. I learned how to make a smooth rifle shoot better here and other things. Like paper cartridges for rifles etc etc.
I HATE doing serious load development anymore. Its not "fun" to me. But it must be done from time to time.
Now I need to seriously "develop" the trim in a closet.... Before my wife gets home ;D
Dan
-
I also believe that if given a place expand laterally they will.
Now if that soft lead ball had a slightly larger surrounding at the breech than the muzzle, when it "bumps up" it will, in effect, be re engraved as it travels towards the muzzle.
Thus providing a tighter grip on the PRB by the lands all the way to the muzzle. What I am talking about here is a tapered bore.
Now THAT seems to make a lot of sense...
Yes - this is, as it happens and why choked barrels usually show slightly better accuracy than non-choked. I proved this to myself back in the mid 70's when I was in the sport only a few years. A constant taper I'm not sure of, though - at least with a lot of difference between groove AND bore diameters, muzzle back to breech in both borer and grooves.
My own Military Replica barrel with a tapered groove diameter of about .006 to .008" difference or so, doesn't burn patches in the least, yet ball with patch having been swaged to a maximum diameter of .580" at the muzzle when seating, become quite loose in the breech's groove diameter, where the measurement is perhaps .596" groove to groove - yet - there is no burning of the patch - indicating there must be some obturation due to the inertia factor. Note, in this barrel, the bore's diameter remains constant and only the grooves have tapered depth, from .003" at the muzzle to .011" at the breach. Although it is designed for easily expanding conicals with hollow bases, it shoots exceptionally well with patched round balls (which it shouldn't) and with solid pure lead slugs which also appear to fill the grooves just fine upon discharge. Loading and shooting 10 rounds of slugs, then a tightly patched round ball shows no difficulty in loading. if there was no obturating in this bore, solid lead slugs would lead the bore due to the fire blasting past, melting off lead and spraying the molten lead into the bore ahead of the bullet, which then irons it into the bore when it passes. With patched balls, no obturation would burn the patch and perhaps even lead the bore as well - yet - no leading, no burnt up patches and great accuracy with both.
There is probably a gradual scale of ball weights/sizes where obturation does take place due to the resistance to movement solely due to mass of the ball - as noted in previous posts. This is reasonable and shows common sense. Obturation of the bullet is due to the level of pressure in concert with the alloy of the ball or bullet. This is common knowledge amongst cast bullet shooters and there is a formula which will show at which pressure, different alloys will obturate as the pressure overcomes their resistance due to their compostion. I seem to recall WW allow requires something in the realm of 24,000PSI before it will expand - and this is with bullets. The formula does not take into consideration the mass of the projectile nor the size - it is simply mathematical - at "X" pressure, there will be obturation - below that pressure, there will be none. It is entirely possible my common sense is in error and math proves to be correct.
I realize this post is in lay-terms, but I obtain a better understanding using examples of the topic which show pictures. Yeah - compared to others in this thread, I lack their scientific knowledge and verbage in posting, but do understand the posts and their content - I think? - (yes- a question)
-
Obturation pressure = 1440 X BHN
http://www.sixguns.com/crew/obturation.htm
-
Thanks Dan - that's it.
-
I mentioned a Green River Barrel that did not seem to want to shoot. They were choked and I think that was the problem as I remember it started shooting well at 140 grains (it was a 58). The ball needed that to obturate is what I am now thinking from reading these posts. It also liked a very thick patch and a 575 ball. I did not like what it seemed to like so I sold it.
DP
-
Mine also DP. At 140gr. it shot incredibly well, but then, my other .58's also preferred 120gr. and up. Even though mine was a heavy gun, that narrow Hawken guard was just too oncomfortable for me to keep the rifle. Any position other than offhand was murder. On an English-styled gun, the same caliber with 140gr. would have been a moderately heavy load only- nothing to write home about. The obtruation deal might have been a part of this. Smaller calibers create much heavier pressures with seemingly"light loads- in comparrison.
I-too used a .575" ball and a .022" denim patch - same with all my .58's that had a .580" bore.
-
The problem with the "obturation pressure" thing is that smokeless is seldom fast enough. I KNOW for example that in a 44-40 FFG Goex (IIRC) will make more pressure in the CYLINDER than Unique will at 7-8 grains, though the smokeless will produce equal or higher velocity with a barrel installed. Shooting a SA Colt with no barrel in the frame can be VERY enlightening.
The pressure curve and initial acceleration is just wrong to bump lead bullets before gas cutting occurs. Smokeless at 45 colt pressures does not make the pressure at the right TIME to prevent gas cutting if it EVER does.
A 45 Colt with WW alloy and 231 powder, 7.1 gr (factory dup load). Simply will not bump up in the cylinder with a 250-260 gr bullet NO MATTER THE ALLOY. One SAA 45 Colt I had, a Cavalry Comm. had a .457-.458 cylinder throat. It gas cut to beat the band with smokeless and .452-.454 bullets. Also leaded the barrel. Finding an old Keith mould that threw oversized bullets cured the gas cutting but the .451 bore leaded beyond the forcing cone. It shot wonderfully for about 4-6 shots then went to the level of the gas cut bullets there simply was no work around other than jacketed bullets which at least did not lead, still shot like $#@*. So I sold it to a Cavary Re-enactor (the wagon driver that got "stuck" while crossing the river in "Dances With Wolves") and he of course was thrilled.
However, I had a 38-40 Colt with 400 cylinder throats and it would bump the bullet in the *forcing cone* with 7+- grains of 231 and fill the .405 bore, but sometimes the rifling would be longer on one side than the other on recovered bullets....
So far as the heavier bullets being faster than the lighter ones on the website linked above. I wonder if the researchers thought of the idea that maybe the heavier bullet raised the *pressure* a little. Since they were using the same powder charge it HAD to. So I consider this little write up just about useless based on my experience with numerous 45 colt 38-40 and 44-40 revolvers. Also in my experience if the bullet gas cuts it leads at a wonderful rate so if the bullets were gas cutting they would have known it. Had they looked at recovered bullets for gas cutting it might have bolstered their argument. But I figure in that many 45 Colt revolvers they had to have 1 or 2 at least with OS cylinder throats that are probably gas cutting everything they shoot. But they might be really lucky in this regard.
Funny thing is BP WILL bump bullets smokeless will NOT when loaded to the same velocity+-. It also will not gas cut since they obturate just as the bullet starts to move. BEFORE it leaves the cartridge case.
Yes, I suppose that certain smokeless powders will reliably "bump up" bullets. I just don't know of any.
Those who doubt me should try shooting .457 bullets in a TD Springfield, Sharps etc with a .464+ bore and see if they can make it shoot with smokeless.
Dan
-
Dan,
The formula referenced is, in my opinion, one of those "rules of thumb" that has floated around for some time. I have no idea who contrived it, but there are certainly aspects of obturation not addressed, such as sectional density. There is little doubt in my mind that regardless of firearm, powder or charge, conicals will obturate more at a given pressure than PRBs. Logically, those bullets with high sectional density and thus large inertia will obturate more. My own experience with BP and smokeless in rifles seems to be consistent with the formula. My single foray with smokeless and paper patched bullets in a RSB did as well, but they were full house loads...as in bring the earplugs Mabel. Shot quite well too. With that said, I don't believe anyone here doubts that Lord Black will cause obturation.
The question we consider then is just what circumstances contribute to load inertia in PRB rifles, and I accept without deep consideration that obturation is a factor of substantial note. There is a question in my mind as to what degree a round ball will obturate and if heavier charges have a linear or geometric influence. It would seem to me, and this is a guess, that several strings registered over a chrony and using increasingly hard alloys would reveal some of this. I also guess that the effect might be more dramatic in a tapered bore rather than straight. Don't know this is a legitimate approach but I would think two rifles, one with taper, one without, fired in a series of strings in two paths might do it. One would use BHN 5 lead with incremental increases in charge while the second would use a constant charge with incremental increases in BHN, say 5, 12, 20? One or the other, or both, will at some point indicate a trend of reduced or increased velocity standard deviation I think.
There is an article in the recent edition of BPC News regarding the .25-20 SS by Herr Garbe. Now this may or may not be meaningful in context of our discussion, but it occurs that perhaps it is. The point he made went to reduced SDs resulting from charge compression AND the milder small pistol primers. He wondered aloud about the causes of case stretching resulting from hot primers and uncompressed loads as well. Well, I'm not that much of a CSI, maybe it's relevant, perhaps not. ??? You and Mr. Pletcher have indicated reduced SD in BP arms resulting from compression as well, even with muzzle loaders and contrivances to impart same on his part, and drop tubes on yours. Well, maybe there's something in all that worthy of further discussion. Until you had mentioned that, the idea of using a drop tube on my rifles had never crossed my mind. The idea of using my calibrated hammer (my right palm) had.
By the way, there is also an article in the same issue regarding the relative brisance of different brands of primer caps for muzzle loaders...and a few regular types as well if I recall correctly. With pictures!
Stray thoughts from a troubled mind.
-
To my mind there is no consistent way to reduce the velocity variations in a PRB rifle short of compression and perhaps a drop tube or cleaning every shot or using water based lubes or all three.
Fouling is not going to be consistent enough.
In shooting my 54 at 200 a few times I found that ANY feeling of roughness due to fouling caused accuracy problems. So I started dry brushing and damp patching.
I also found that seating the ball flush with the muzzle and cutting the patch there gave better accuracy.
NONE of these things were apparent at 50-100 or I did not NOTICE them. A key point.
The 200 yard groups never showed vertical stringing when loaded this way so I assumed the consistency was good.
I think that PRBs with their low sectional density upset minimally. I feel they "probably" upset just enough the make things work a little better. The problem is in proving it. Its pretty easy in a bulleted gun. A 457125 (govt 45 500 gr bullet) cast soft will upset all the way to the ogive in a ML bore that is .008+ over size. The land marks on the bore rifling nose were not full depth but well pressed in. Alloy was very soft, but this was 30 years ago +- .
A 45 PRB is NOT going to do this. For one thing I believe the patch supports the ball to some extent and if the fit is tight there may be no upset at all.
Larger balls might upset more but I don't think its enough to do more than perhaps tighten the fit slightly and improve accuracy. I suspect a thousandth or 2 at the most.
Getting proof is not going to be easy.
For those that would try to do this the oiled sawdust trap is described in Mann's "The Bullets Flight" pg 59 of my Wolfe Publishing edition. The instructions are longer than I want to type but fine hardwood sawdust was used, it was oiled to the point of saturation but not dripping. It should not clump. They sifted the sawdust to make it uniform. It takes a LOT of oil and for PRB I suspect that 12x12x36 box will be needed to stop the bullet. The front would likely need to be very light cloth. With heavy loads the box would need to be shot at 75-100 yards to reduce chances of expansion.
They used light machine oil but I suspect that 5w or 0W30 etc motor oil or light hydraulic oil/"tractor transmission oil" from Wally World would work OK. Oils that might gum up should be avoided.
Dan
-
I have the book and will ponder your thoughts...as I review some other information. I have seen photos of PRBs just clear of the muzzle that were obviously deformed in consistent fashion with obturation. Don't recall the caliber though. ??? My gut says any support offered by the patch will extend only to the point the material is fully compressed and that is a variable black hole. The earlier testimony about tapered bore rifles shooting better with heavy charges indicates PRBs do obturate...in my opinion.
Clean barrels are uniform certainly. I'm puzzling about ways to play with fouling in a uniform way from shot to shot that does not require surgical cleanliness.
-
I read in a BPC publication that using BP one should not consider a 45 70 a Short in a longer chamber like a 45 by 2 7/8 as it upsets to the chamber and then has to be resized hitting the bore. Some use them that way with smokeless but they stated it should not be done with BP. Maybe the little bit RBs upset is why pure lead is more accurate. In a good barrel, by the time the patch ball combo reaches the breech after a long push one tends to notice a little easier seating unless the bottom area gets fouled. It would not take a lot of upset to refit the tight fit to the bore. A cartridge has a press fit of bullet to case that also helps pressure build. Consider that if we would make a pressure gauge on a ramrod and seat the ball (or bullet) in a ML, would we maybe not get a "bounce back" as the fit is no longer tight enough to maintain the pressure and have at best uneven resistance? This would especially be true in a choked barrel.
DP
-
Dpharris- I believe your last post pretty much says it, in regards to obturation of a round ball and the amount thereof. There is no argument about the expansion of elongated projectiles - even short ones like the REAL bullet or short picket bullets. Sectional Density certainly helps. It is interesting, the amount of powder needed to obtain good accuracy with the pickets ( low SD) - example in .40 cal. picket 80gr. powder. The shorter the projectile, the greater must be the pressure to obtain obturation. Carry this to what we see as the extreme - the round ball.
Now, enter the rifled Foster slug as loaded in factory shotshells is pure lead, lighter than the same size in round ball, so it should be less prone to obturation - however, due to the hard wad support beneath, it's very thin skirts like a 'Minnie' ball & and very fast burning, fast pressure rising shotshell powders used today, this slug obturates to fill even .730" bores, presssing the rifling out flat in some bores and even to complete obliteration of the grooves. This I've seen and tested myself. RP slugs did the same, even though they were much smaller back in the 80's, when they were a mere .690" in diameter, expanding out to a full .725", the size of my double's bores.(tight 12). So - some smokeless work to obturation in a similar fashion to BP due to an extremely fast pressure rise in the LARGE bore, whereas most smokeless powders don't.
Obturate is the correct word - Pocket Oxford- stop up, seal,(orifice in body, breech of gun) - obturation-noun; obturator-noun; obturating-applicance-noun.
Obdurate, as I've seen in books on muzzleloading explaining what happens to the ball upon ignition, instead of obturation - obdurate -adjective - hardened, stubborn; obduracy-noun
-
DP - you have a good point - that the patched round ball will not maintain pressure and is easily moved.
Failure to lift the hammer to 1/2 bent postion and remove the cap from the nipple in a cap gun, causes an air compression between the patched round ball and nipple/cap seal that causes difficulty in pressing the ball down and also causes the ball to rise back up the bore if the presssure is not released by the removal of the cap or lifting the hammer to 1/2 bent.
-
If pressure is applied to a round ball thus;
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fmikealee.home.mindspring.com%2Fimages%2FMLStuff%2Frb%2520obturation.JPG&hash=13f378a19f915886473f61b46acf71e8294392ef)
Then how can it be expected to "bump up"?
-
If pressure is applied to a round ball thus;
Then how can it be expected to "bump up"?
Its the initial acceleration that causes the ball to deform, assuming it does very much. The pressure just causes the the acceleration which, if fast enough, moves the back faster than the front and causes the projectile to deform.
In digging balls out of back stops I can say that the marks put on the ball by the lands look no different than one started in the muzzle and then pulled back out. But its impossible to measure a ball shot into any surface that will cause it to deform on impact.
This is why the oiled sawdust thing would be great.
Now an undersized bullet such as a 500 gr 45 will show obvious signs of complete upset to fill the bore.
The patched bullet is a little harder to read. I would love to see what e of the 40 caliber pickets looks like as it clear the muzzle but they do not survive back stops well at all.
Dan
-
Dan, Dan, Dan, Dan - your fit is much too loose & the pressure arrows coming from outside the bore! - just kidding. It is a graphic reminder of how the pressure actually is present in pushing on the entrie base of the ball as well as inwards on the bottom ogive. We know from research, that boattailed jacketed bullets are tougher on bores and throats than are flat based bulles, due to the powder gasses exerting pressure against the angles of the base, being directed up the slope towards the fit into the gooves and perhaps bouncing back against the bore itself.
The fact remains boattailed bullets are tougher on bores and actually obturate less than does a flat based bullet. Perhaps the same re-direction of powder gasses happens to the patched round ball or picket bullet's rounded base, however one might think no patch could survive if that did happen, yet the patches most certainly do. What gives?
The more I think about this, the less I think obturation actually takes place with round balls, yet why do some people's drop-the-patched-ball down-the-barrel seem to shoot OK, without obturation happening at least slightly? Now, 'seem to shoot OK' might need clarification as a lot of different people have different ideas on what OK accuracy actually is. Perhaps even some re-inactors think their loads are accurate as did the fellow shooting .30/30 cases full of sand.
I would think the tighter the ball is held in the bore by the patch, the more the powder charge must manifest itself to get that 'tight' ball moving, yet such balls are very easily pulled when a, shall I say it, dry ball occurs leaving one to think a badly fouled bore actually grips the ball harder than does one just cleaned by a tight fitting combination being seated. And no - no hammer or mallet is needed - a starter is handy & makes loading quicker.
-
Its the initial acceleration that causes the ball to deform, assuming it does very much. The pressure just causes the the acceleration which, if fast enough, moves the back faster than the front and causes the projectile to deform.
I agree with that.
I do not believe your diagram is properly representative of the pressure acting on the ball. The pressure, or force vector, would properly be depicted in context of its action perpendicular to the cross sectional area of the ball and parallel to the bore, vector oriented toward the muzzle. The way it is depicted in the diagram would lead one to believe there is force applied on the ball, perpendicular to the bore, or close to it.
I have a fairly busy schedule over the next two months but after mid June I will have some time to play with this. I see a sawdust and oil box in my future. ;D
If anyone wants to set procedures let me know what you think appropriate....purpose being an attempt to quantify PRB obturation...in a .45 cal. flintlock, straight bore. I have pure lead balls, .440 and .445" and patches ranging from .005 to .025". Anyone having moulds that will cast alloy to the same dimensions and can establish BHN, I'll run with that too.
After some thought on the matter I withdraw the picket rifle from the endeavor because I ain't got a clue how to measure diameter on a ball shot through odd number grooves.
-
Daryl's comments on the boat tail also indicate a round ball may have more problem obturating unless really driven with a heavy charge. Also consider that for ML's the Minnie bullet was quite a breaktrough for the military. The Lee Hollow base bullet is popular for old Springfield 45-70's with their varying bore dimensions. When one looks at the target shooters use of lapped barrels we also see another variable in the picture. Lapping is done to try to get the bore even in diameter, they polish out and try to eliminate tight spots. A bullet of what ever design will resize to the narrowest part of the bore. Musket shooters also have determined that a Minnie is not all that inaccurate if it slightly engages the lands as compared to the sloppy military fit.
DP
-
Its the initial acceleration that causes the ball to deform, assuming it does very much. The pressure just causes the the acceleration which, if fast enough, moves the back faster than the front and causes the projectile to deform.
In digging balls out of back stops I can say that the marks put on the ball by the lands look no different than one started in the muzzle and then pulled back out. But its impossible to measure a ball shot into any surface that will cause it to deform on impact.
This is why the oiled sawdust thing would be great.
Now an undersized bullet such as a 500 gr 45 will show obvious signs of complete upset to fill the bore.
The patched bullet is a little harder to read. I would love to see what e of the 40 caliber pickets looks like as it clear the muzzle but they do not survive back stops well at all.
Dan
Hi Dan,
I am looking into a method of studying this that involves a photo flash of amazingly short duration. This flash has photographed a modern bullet at 2800 feet/second clearly enough to examine the rifling marks. If such a tool could be used, we could simply photograph the ball/bullet as it leaves the barrel. I can do this now with a ball at 1000 fps, but at real world speeds one needs something more.
Regards,
Pletch
-
Just as an observation I've detected patch weave marks on fired lead balls on occasion. Since recovering a fired ball is a rarity, I can't say if this is an anomaly or not.
-
Weave patterns on the ball will Always occur with a .005" under ball and a .025" patch.
-
Weave patterns on the ball will Always occur with a .005" under ball and a .025" patch.
This is a .530 ball and .023 patch.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fmikealee.home.mindspring.com%2Fimages%2FMLStuff%2Frecovered%252054ballback.JPG&hash=ae564765615e88ada45650c43eca1e4c407421ae)
Weave is imprinted all the way around the ball to the mid point.
I am looking into a method of studying this that involves a photo flash of amazingly short duration. This flash has photographed a modern bullet at 2800 feet/second clearly enough to examine the rifling marks. If such a tool could be used, we could simply photograph the ball/bullet as it leaves the barrel. I can do this now with a ball at 1000 fps, but at real world speeds one needs something more.
Seems like there will need to be a way of determining if any change in shape happened during loading or shooting. Maybe one could load a few balls and pop them out with the patch material at the muzzle or shoot them into a medium with five grains or less of powder? ???
Its the initial acceleration that causes the ball to deform, assuming it does very much. The pressure just causes the the acceleration which, if fast enough, moves the back faster than the front and causes the projectile to deform.
True, the ball can only accelerate in one direction. However, the pressure all around the ball up to the equater is attempting to cause the ball to accellerate and therefore serving to nullify the deformation in any direction.
I got absolutely no way of proving this theory. It's just the way I think about it. :)
I do not believe your diagram is properly representative of the pressure acting on the ball. The pressure, or force vector, would properly be depicted in context of its action perpendicular to the cross sectional area of the ball and parallel to the bore, vector oriented toward the muzzle. The way it is depicted in the diagram would lead one to believe there is force applied on the ball, perpendicular to the bore, or close to it.
That would be appropriate in the case of a flat based projectile, but the pressure can't help but surround the ball and apply pressure all around the under side half of the ball. Ultimately the gasses (pressure) travel and are expelled parralell to the bore but That would not seem to change how the pressure is applied to the ball.
-
Hi Dan,
I am looking into a method of studying this that involves a photo flash of amazingly short duration. This flash has photographed a modern bullet at 2800 feet/second clearly enough to examine the rifling marks. If such a tool could be used, we could simply photograph the ball/bullet as it leaves the barrel. I can do this now with a ball at 1000 fps, but at real world speeds one needs something more.
Regards,
Pletch
Hi Larry
Once the smoke problem was defeated this is an excellent idea.
Might have to photo the ball a few feet from the muzzle.
I have been on both sides of the upset in RBs issue. I used to be on the no upset side, now I am not so sure, still would not put money on either theory. I really doubt the typical 54 rb is going to upset with FFG powder I think its too slow. FFFG might and I suspect this might be why some of the 54-58 cal guns shoot FFFG better.
But the upset may be just enough to make a slightly tighter bullet fit at the lands. Its certainly not something that is going to seal the bore.
I have tried to recover a piece of a 132 gr 40 caliber picket bullet since this really should upset. Flat base, more weight for bore size. But it shoots best with pretty heavy powder charges and the pure lead pickets are just lumps of mangled lead even at 100-120 yards. The one piece I did recover did not seem to have upset at all. But the damage was such that its impossible to really come down on one side of this or the other.
Needs more experimentation or an oiled sawdust box or pictures.
Dan
-
Hi Larry
Once the smoke problem was defeated this is an excellent idea.
Might have to photo the ball a few feet from the muzzle.
I have been on both sides of the upset in RBs issue. I used to be on the no upset side, now I am not so sure, still would not put money on either theory. I really doubt the typical 54 rb is going to upset with FFG powder I think its too slow. FFFG might and I suspect this might be why some of the 54-58 cal guns shoot FFFG better.
But the upset may be just enough to make a slightly tighter bullet fit at the lands. Its certainly not something that is going to seal the bore.. . .snipped . . .Needs more experimentation or an oiled sawdust box or pictures.
Dan
Hi Dan,
I'm sure you remember the questions I sent your way working on this patch separation project. If velocity and flash limitations don't get in the way, the current topic could be a logical extention of the patch/ball separation work.
(.40 caliber ball app. 26-30" from muzzle about 1000 fps)
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi93.photobucket.com%2Falbums%2Fl72%2Flpletch%2FPatched%2520Ball%2520Pics%2Fpic19.jpg&hash=35d3a209b37bcac2b6ee2a1ff9eb6a75af6419fe)
In the pic above I had the additional problem of trying to focus the camera at a shorter distance. I have a camera now that will do much better. If I were to repeat the photo above with my current camera I could pretty much fill the frame with patch and ball.
Assume that we had a ball/patch combination that left cloth marks on the lands but not in the grooves when we loaded it in the muzzle and pulled it back out by the cloth. If we could get a photo that showed cloth marks in the grooves as the ball passed the camera, we could logically say those cloth marks were caused by the bumping up of the ball when it was fired.
The biggest problem with this would be the short duration of the flash. The photo above was fired at 1000 fps. I'm sure that we would need to fire a ball at a much higher velocity to approach a speed where any bumping up would occur - if any did. As the velocity increased, we would likely begin getting an elongated ball. The flash system I described in an earlier post was one whose flash duration was measured in millionths of a second. We don't need to stop an '06 at 2800 fps but we might need to get to 2000 fps to see any cloth marks made during firing - again - if there are any. If I'm lucky I may get some contact info on such a flash. Normal flashes don't come close. The one I used for the pic above was "tampered with" a bit.
Regards,
Pletch
-
Quote
I do not believe your diagram is properly representative of the pressure acting on the ball. The pressure, or force vector, would properly be depicted in context of its action perpendicular to the cross sectional area of the ball and parallel to the bore, vector oriented toward the muzzle. The way it is depicted in the diagram would lead one to believe there is force applied on the ball, perpendicular to the bore, or close to it.
That would be appropriate in the case of a flat based projectile, but the pressure can't help but surround the ball and apply pressure all around the under side half of the ball. Ultimately the gasses (pressure) travel and are expelled parralell to the bore but That would not seem to change how the pressure is applied to the ball.
You are correct about applied pressure, I was confusing terminology in the previous. It is however, the force and resultant acceleration vs. resistance to same(Sectional density/inertia) which promotes obturation.
Frankly I am quite certain that PRB do not obturate to the degree found in conicals, however, it is a long leap to imagine they do not obturate to some degree. Question is, how much?
-
Dan- how much goes back to the load - finer (faster) powder as Dphar suggests vs. coarse (slower) powder. Indegree, I agree it might happen, but not much more than a couple thou. This is difficult to prove, of course. As suggested, what would be needed is a ball/patch combination that doesn't go to the bottom of the grooves - maybe .001" short of that and photgraph with a descent charge to see if the ball is marked by the bottom of the groove & if so, then go with .002" short of marking in the bottom of the groove, etc. to 'catch' the amound of obturation. BUT - that conclusion would only be valuable for that rifle barrel, ball and patch. Antoher load, a bit looser or tighter, or different calibre might not obturate and if it did or not, would have to be retested.
-
Frankly I am quite certain that PRB do not obturate to the degree found in conicals, however, it is a long leap to imagine they do not obturate to some degree. Question is, how much?
Like DanP, I've been on both sides of the question and still am not sure what to think. Just throwing out food for thought.
Pletch might be on to something with his attempts to phota weave imprints in the grooves!
-
Dan- how much goes back to the load - finer (faster) powder as Dphar suggests vs. coarse (slower) powder. Indegree, I agree it might happen, but not much more than a couple thou. This is difficult to prove, of course. As suggested, what would be needed is a ball/patch combination that doesn't go to the bottom of the grooves - maybe .001" short of that and photgraph with a descent charge to see if the ball is marked by the bottom of the groove & if so, then go with .002" short of marking in the bottom of the groove, etc. to 'catch' the amound of obturation. BUT - that conclusion would only be valuable for that rifle barrel, ball and patch. Another load, a bit looser or tighter, or different calibre might not obturate and if it did or not, would have to be retested.
That is the problem. There are huge combinations of variables. One would only be able to say that with this particular set of variables this is what happened. If this is approached looking for a clear cut answer that applies across the board, we'll not find it. We might be able to say that obturation takes place within a very narrow environment of variables. Or maybe not. ;)
Regards,
Pletch
-
That is the problem. There are huge combinations of variables. One would only be able to say that with this particular set of variables this is what happened. If this is approached looking for a clear cut answer that applies across the board, we'll not find it. We might be able to say that obturation takes place within a very narrow environment of variables. Or maybe not. ;)
Regards,
Pletch
[/quote]
Agree - completely.
-
The possibility of measuring obturation with photos got me thinking about the methods. I played around a little to see what kind of problems might have to be overcome. The ability to get close enough and in focus can be solved. The pics below should give us a close enough look to see cloth marks - if any are made. On the first I left the ball unmarked. In the sceond I rolled the ball over a rasp. They both make me think cloth marks will be visible.
(Obviously these are taken of a motionless ball.)
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi93.photobucket.com%2Falbums%2Fl72%2Flpletch%2FPatched%2520Ball%2520Pics%2FNew%2520try%2FIMG_2115.jpg&hash=6eff2c2e83edd8cd52cf06b30251d01c6c15db93)
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fi93.photobucket.com%2Falbums%2Fl72%2Flpletch%2FPatched%2520Ball%2520Pics%2FNew%2520try%2FIMG_2123.jpg&hash=dbead3b5ac076475224e64f6c0fd32e5d121914b)
The photo will be done by the ball breaking an infrared beam to trigger the flash. I have done that before. Takes some set up time, a benched rifle, and a good man behind the gun. I have all three.
The remaining issue is what happens when the ball is traveling at speed. I can stop a ball traveling 1000fps, but have not tried faster. I don't know the extent of the blur could be present. Only time will tell. Flash duration needs to be short. Mine can be manipulated. We'll see.
Regards,
Pletch
-
Good luck on an interesting project, Larry.
-
Advanced notice.
This is an uninformed, out of the box idea.
Is there any way to test the patch material for the presence of lead at bore contact points?
i.e. does the lead ball impresses itself INTO the cloth with varying "density" and if so can it be made to "show up" in a CSI type test?
A solid ring of lead residue would imply a fattening of ball into grooves.
A dashed ring means lead was not pressed into grooves.
Maybe put some sort of micro-thin coating on the ball and test for that?
Just thinking out loud.
-
Advanced notice.
This is an uninformed, out of the box idea.
Is there any way to test the patch material for the presence of lead at bore contact points?
i.e. does the lead ball impresses itself INTO the cloth with varying "density" and if so can it be made to "show up" in a CSI type test?
A solid ring of lead residue would imply a fattening of ball into grooves.
A dashed ring means lead was not pressed into grooves.
Maybe put some sort of micro-thin coating on the ball and test for that?
Just thinking out loud.
That is an idea that I had not thought of. I'm not familiar with how a test for the presence of lead would work. There may be folks in this group that know. Maybe someone can fill in some gaps. Thanks for thinking out loud.
Regards,
Pletch
-
Advanced notice.
This is an uninformed, out of the box idea.
A solid ring of lead residue would imply a fattening of ball into grooves.
Just thinking out loud.
I am sure that is what happens every time I load. The lands and grooves impress into the ball, all the way around. I suspect is some sort of lead testing was done, it would show microscopic traces in a line around the patch/ball contact, heavier on the land areas, just as the impressions appear on the ball.
-
Maybe this problem can be submitted to MythBusters and have them do all the work! ;D
Actually, I am really looking forward to seeing some testing from the real experts here.
-
I just tried starting both .490 and .495 balls into each of my two fairly fresh Lyman GPR rifles.
Pulled out the flush ball by tugging on uncut pillow ticking patch material.
There is no trace of impressed cloth pattern on any part of the ball except where the lands are.
i.e. the grooves did not press cloth pattern into the lead ball.
-----
Google returns a a site on lead residue testing in police work.
http://www.firearmsid.com/A_distanceExams.htm (http://www.firearmsid.com/A_distanceExams.htm)
The sensitive chemical is "sodium rhodizonate".
Maybe some commonly available home test kits have it. (for lead paint etc.)
I looked at all the labels on my breakfast cereal, toothpaste, potato chips, chicken soup, etc hoping to find a cheap source for this stuff but no luck so far.
-
I always thought the gray ring on the ball side of the patch (bottom couple of rows) WAS lead...
I've thought it to be fouling wiped off the bore and into the patch while loading.
-
I just tried starting both .490 and .495 balls into each of my two fairly fresh Lyman GPR rifles.
Pulled out the flush ball by tugging on uncut pillow ticking patch material.
There is no trace of impressed cloth pattern on any part of the ball except where the lands are.
i.e. the grooves did not press cloth pattern into the lead ball.
-----
Google returns a a site on lead residue testing in police work.
http://www.firearmsid.com/A_distanceExams.htm (http://www.firearmsid.com/A_distanceExams.htm)
The sensitive chemical is "sodium rhodizonate".
Maybe some commonly available home test kits have it. (for lead paint etc.)
I looked at all the labels on my breakfast cereal, toothpaste, potato chips, chicken soup, etc hoping to find a cheap source for this stuff but no luck so far.
Powderman - had you used a tighter ball/patch combination, there would have been cloth marks from the grooves as well.
-
Larry, I would imagine you can get some traction with photographic analysis on this. It is not my area of expertise by a long shot, but I note the boys working in the gubermint labs such as Aberdeen and use photos and mm wave length radar to ascertain painfully small measurements of pitch and yaw on conical bullets. Good luck with it in any case....I shall of necessity stick with the medieval technology of oiled sawdust boxes.
-
Daryl - I doubt that many typical shooters use a ball that is more than 0.005 under bore size.
i.e. a .495 RB in a .500 (land to land) bore.
I'm not sure what the groove depth is for sure but "think" it's like 0.005-0.010.
Larger than .495 (for 50 cal) is not available in most stores.
The pillow ticking was typical as found in yardage stores.
i.e. about 0.015 thick.
I can forcefully compress it with my micrometer down to maybe 0.004
I'm not using a mallet to start the ball just a short starter and a hard slap.
I can't push the ball in with my fingers.
I think the gist of the question here is, shooting a normal PRB combination, is there any obturation or fattening of the ball when fired. And if so, how much. And what parts do lead purity, loading compression, powder charge/granulation and fouling play. What provides resistance at the moment of ignition to assist in obturation if any.
Also, when I pulled the ball there was no obvious evidence of lead on the patch material. I took a ball and rubbed it hard back an forth on the patch material and was then able to see some lead deposited. Some looked like flakes from a file.
Just abrading by cloth which wouldn't occur in the barrel.
I tend to agree with longcruise that the readily visible stuff on the patch is probably fouling residue and lube/spit absorbed into the cloth.
But who knows for sure until some bright guy here can figure out what's actually going on through testing with the right skill and equipment?
I'm looking forward to it as much as I appreciated the high speed video/data of flintlock ignition. Incredible.
-
This is interesting.
I just found another thread, on a different Forum where several people said:
*They could not find any cloth impression marks in the GROOVE area of the ball.
*They could not find any cloth impression marks in the LAND area of the ball.
(Maybe see a little with a magnifying glass)
*No obturation occurs in PRB since they didn't see any cloth patch weave marks even on fired balls recovered from various sources.
I thought maybe they were talking about the backside of the ball.
I don't think so since one guy was talking about shooting marbles with great accuracy.
When one guy mentioned that he pulled balls and saw weave marks, someone said that it was the screw-type ball puller had expanded the ball and forced it into the rifling.
http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/223136/post/593197/hl/obturation/fromsearch/1/#593197 (http://www.muzzleloadingforum.com/fusionbb/showtopic.php?tid/223136/post/593197/hl/obturation/fromsearch/1/#593197)
Go figure.
If testing is done make sure you document the condition of unfired, pulled balls.
Post modified as per forum rules.
Daryl
-
This is interesting.
I just found another thread, on a different Forum where several people said:
*They could not find any cloth impression marks in the GROOVE area of the ball.
*They could not find any cloth impression marks in the LAND area of the ball.
(Maybe see a little with a magnifying glass)
*No obturation occurs in PRB since they didn't see any cloth patch weave marks even on fired balls recovered from various sources.
Oh brother....
I strongly suggest that before you believe this "information" that you do your own research.
Bigger balls show more cloth imprint than smaller balls will.
Unless very loose fits are used all will show marks where the lands impress the patch into the ball.
One other thing seldom have I had to screw a puller very deep in the ball to pull it.
But then I know how....
In a 54 ball you need to turn it in past the 1/2 way point to swell it at the point where the lands bear on the ball.
Dan
-
I think you all realize that there isn't going to be a quick, easily found answer to this. There are many issues to solve other than the ability to get a decent photo. But, that's where I'm likely to start - if I can't get a photo that shows cloth marks on the lands, I certainly won't be able to photograph cloth marks in the grooves.
We will likely use a .58 belonging to Steve Chapman, who will be the man behind the gun. (He has to fire the shot, stacking one ball on top of another in a completely dark room. :) BTW, that's the least of my worries.) I want a ball/patch load that shows cloth marks on the lands at 1000 fps in clear focus. That will be the control for our basis of comparison - both for flash issues and for the amount of cloth marks. If we are successful with this, then we can continue.
In going beyond, lands and groove depth and width must play a huge part of this. The best I know is to adapt as we begin to get information.
This is going to be on the back burner for a short time at least. We're doing some last minute work this week getting ready to do our flint vs percussion vs mule ear timing. Steve and I don't think this will be a long drawn out process, but who knows. (This project was conceived in Jim Chambers booth at Friendship. His pistol kit stock and small Siler locks will be the basics for this along with a custom mule ear made on a s Siler plate.)
Regards,
Pletch
-
I-too look with excitement on Larry's experiment's.
I modified the post above to remove the 'slam' against a forum member. We here have seen his posts on marble shooting and at close range, he is getting good accuracy with what seems a 'fun' load for plinking, for him. I agree, Roundball, that part of the post was certainly unnecessary.
-
I think the gist of the question here is, shooting a normal PRB combination, is there any obturation or fattening of the ball when fired. And if so, how much. And what parts do lead purity, loading compression, powder charge/granulation and fouling play. What provides resistance at the moment of ignition to assist in obturation if any.
Our normal loads use a ball .005" under, with a .020" to .025" denim patch - compressed with a mic. A pair of calipers will give measurements .003" to .005" thicker, compressed between the fingers, not just with a thumb on the slider and using the wide part of the tines as the contact surface.
I have some pre-lubed pillow ticking, marked .018", however it's only .012" by my mic., .015" with my calipers.
We don't use mallets, only a starter, sharp smack, or by using the short stud on ball and a smack of the palm on the opposite side. This puts the patched ball down 1/4" to 1/2" depending on the length of the stud. From there it is advanced down the bore with the long shaft of the starter. It may, if you prefer, be loaded as Dphar showed in his video, by just using the rod, but after it is pushed into the bore far enough to make the patched ball, fit the bore. Just fir fun, I loaded a few as Dan does, using my .40 (.398" bore) with a .0215" (mic'd) denim patch and .396" round ball. The ball is only .002" smaller than the bore, yet using Dan's process, it was loaded with the 3/8 hickory rod. I prefer to use a starter, as it's easier & faster loading.
In using a long strip of cloth seating the ball some 1/2" into the bore, then pulling the ball out by the cloth's tags, it is marked all the way around, lands and grooves - if you use a substantial patch and a large ball.
In the .577 Musketoon (progressive depth rifling), with it's .574" bore and .003" rifling at the muzzle, a .575" ball, even with a thin .013" denim (mic'd) patch, will show heavy cloth impressions all the way around the ball, land and groove. It shoots very accurately, but - since the groves are .008" deeper at the breech, obturation would seem to be necessary to fill the rifling depth at the breech. The barrel does not to foul for a day's shooting with no wiping at any time, even though the ball/patch is .008" 'loose' on each side, at the breech - perhaps they do obturate - some?
-
Methinks this is getting some interesting thought.
I think you all realize that there isn't going to be a quick, easily found answer to this.
YEP!
On the matter of ball size vs. bore size, I have used .440" balls in a .450" bore quite a bit and they shoot well with a .010" patch. Perhaps a bit better with .015" patch but it's hard to make that call with offhand shooting from one day to the next. Both are far better than minute of deer heart at 50 yards and that has been my only litmus to date.
There is much to ponder and perhaps most will only be determined on the line rather than here. Some of it, such as the effect of a ball screw might not be so difficult....
-
It may, if you prefer, be loaded as Dphar showed in his video, by just using the rod, but after it is pushed into the bore far enough to make the patched ball, fit the bore. Just fir fun, I loaded a few as Dan does, using my .40 (.398" bore) with a .0215" (mic'd) denim patch and .396" round ball. The ball is only .002" smaller than the bore, yet using Dan's process, it was loaded with the 3/8 hickory rod. I prefer to use a starter, as it's easier & faster loading.
It seemed to load a harder than "normal". Could be this batch of ticking is little thicker than what I had been using, the rifle had not been shot since 2007 so this batch of patching might be a little thick. I hardly ever measure the stuff so this is possible.
I should have loaded a 530 too I guess.
Dan
-
Methinks this is getting some interesting thought.
On the matter of ball size vs. bore size, I have used .440" balls in a .450" bore quite a bit and they shoot well with a .010" patch. Perhaps a bit better with .015" patch but it's hard to make that call with offhand shooting from one day to the next. Both are far better than minute of deer heart at 50 yards and that has been my only litmus to date.
Dan- please note the target shot in this post from the accuracy thread. It shows both bench and offhand targets shot with tight shooting load and those of lesser accuracy. It shows a load that groups closely, does so offhand as well, and one that spreads, falls apart when shot offhand - just as expected.
http://americanlongrifles.org/forum/index.php?topic=4307.msg41908#msg41908
-
What often happens in any shooting is what a friend calls "the law of compensating errors.
If the errors compensate. The shooter is off to the left and and the ball off to the right making a center shot.
In limited testing, one group of a group of 3-5 shots can result in the fliers from the group being well placed and making the load look better than it is. Thus serious accuracy testing requires 20 shots or more to prove the accuracy.
In offhand shooting a shooter might not be aware of a poor load if he does not have the offhand skill to know when a shot is "off or on".
If the shooter calls the shot low left and is confidant of the call and the shot goes high right the load may be the fault.
So shooting a poor load because offhand "don't matter" is silly as Daryl pointed out.
Dan
-
Not sure how to interpret that actually, or if it is really pertinent to the point. I would expect any load to shoot a smaller group from a rest. My comparison went to the point of a previous comment about ball/bore size and what results, this in context of obturation. Shooting offhand does not validate the accuracy potential, nor is comparable accuracy with different loads invalidated by offhand shooting...in my opinion. Until now I have been viewing demonstrated accuracy in my rifle in context of field use, not scientific analysis of accuracy. I'm not certain the endeavor proposed here on the question of load inertia will assure less dispersion either, but it might answer a few questions about obturation and perhaps management of fouling or charge compression. On point of my comments about small balls and patch thickness, the rifle shoots on average about 2" groups of 5 at 50 yards. Sometimes a bit less and sometimes a bit more. Patch thickness does not seem to influence that within those narrow parameters. I'll hunt with either, any day of the week, and keep my shots within that range until I demonstrate suitable accuracy at greater distance. The image below is somewhat representative of what I'm speaking of but the load specifics are not immediately available. Maybe one patch or the other, not sure. Same day in any case.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv298%2Fmuddler%2F107.jpg&hash=f5c183e3c503422a7a6e3225067c4660c8263cd6)
Whether I'm skilled at offhand shooting is another question entirely but the target below was fired on the same day and it largely self explanatory. Together, the targets represent my standard with each rifle and how I employ each for field use.
(https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv298%2Fmuddler%2F107tricks004.jpg&hash=4c4310d733c7506c152196ef68aba07856b5f2b7)
I guess the thought I had was this: If a .440" ball shoots sufficiently well at a given distance and comparably to a load differing only by greater patch thickness, why? There is an introduced variable that does not seem to have any great effect. Is it the result of obturation or magic?
I was just looking at a couple of balls recovered at the range after a days shooting and pass this along without any conclusions whatsoever. One measures .455" in diameter over what would correspond to the groove diameter, or the raised portion of the engraved rifling pattern. I don't know the groove diameter in the barrel but the bore was pin gauged at .450" and I'll say that is accurate +/- .001". The patch material is very fine weave, type unknown, measuring .010" in thickness. Similar thread count to silk in any case, and it left no discernible weave impressions on the ball. The ball is noticeably flatter on the base than forward part of the ball. It looks like the result of obturation but I won't make that claim, simply because of the nature of the media than stopped it, very soft white fluffy sand. The ball is not appreciably deformed otherwise. The engraved portion of the ball measures ~.015" in length.
The second ball is not so substantially engraved and is likewise unmarred so far as visual inspection reveals. It does not have the appearance of upset. The engraved portion is ~.010" in length. Both were recovered during an early phase of load testing when the charge quantity ranged from 30-50 grains of Goex fffg powder.
Collectively they say nothing concise about the matter of obturation, but at this point, and in context of the thread, they give reason to pursue the question so far as I'm concerned. ???
I am inclined to query what is going on inside the breech end of my rifle since Dan brought it up. Along the way I'll let you know what comes of it.
Dan the Other
-
Good shooting offhand - the only rifle I've been able to shoot offhand like that is the .69. It's short, but heavy barrel just seems to stop in the target - good trigger and instant ignition surely helps. The flinters, both with some muzzleweight, seem to wander constantly and are most difficult to shoot due to the timing required - to tough off as they're coming in - variations in ignition timing will throw shots out. Flinters are certainly a challenge. Of course, they all hold better when they're empty. :D